Electric safety fuse or cut-out



No. 622,5". Patented Apr. 4, |899. W. M. MORDEY.

ELECTRIC SAFETY FUSE 0R CUT-OUT.

(Application med Feb, 15, 1897.

(N0 Model.)

75.- a.. ff e h z J/ j] if 9% "akjw/ ssee j UNITED STATES PATENT OFFICE.

WILLIAM ,MORRIS IMORDEY, OF LOUGHBOROUGH, ENGLAND, ASSIGNOR F ONE-HALFTO JOHN M. ORFORD. OF BOSTON, MASSACHUSETTS.

'ELEcrmcsArerv meson cu'r-ou'r.

srncrnca'rxon ming pm of man rame no. snasn, amd Aprn 4, ieee.Application Ilod February 1U, 1897. Bsrid le. 688,450. (le madam To"vall whom `it may concern.'

Be it known that I, Wmmm Monats Mon- DEY, a subject of the Queen ofGreat Britain and Ireland, residing at Loughborough, in the county ofLeicester, England, have invented Improvements in Electric Safety Fusesor Cu t'- Outs, of which the following is a specification. My invention.has f or its object 4improved means-of constructing safety-fusesespecially suitable for high-tension electric circuits.

Hitherto it has been found necessary or advisable tomake high-tensionsafety-fuses of a'oonsiderable length in order to prevent the formationof destructive and dangerous arcs occurring when the fuses are causedto. melt by the' passage o'f currents greater than they are intended tocarry when used under normal conditions. Various plans haveV beenproposed and used to..further guard ainst the formation of sucharcs. lorexamp e, the fuse (which has usually consisted of one or more wires) hasbeen made to pass through holes, slits, or apertures in diaphragme orother dividing partitions'or screens placed between theterm'inals orends of the fuses. In spite `of these and other precautions thedifilculty of preventing the formation of` dangerousor objectionablearcs has been considerable. The fuses made to meet this diiliculty havehitherto been large, costly, and wasteful of energy. By my invention Iam enabled to make lf uses even for very high tension of a small sizeand which are inexpensive, absorb very little energy, and will break thecircuit without any objectionable arc or risk of short oircuiteven underthe most trying conditions.

In constructing fuses accordin to my invention the fusibleconductor,which consists of a thin wireor itlmay be two or more such wires or astrip of thin foil or sheet metal, (the metal used being preferablycopper in all cases,) is supported in a glass tube or other suitablevessel or box. This tube or vessel is then partly or wholly filledwith-finelydi vided or pulverized non-conducting or badlyconductingmaterial, preferably incombustible or -noninflammable-such as dry chalk,marble, bath-brick, sand, mica, emery, asbestos, or the like-thismaterial being made to cover and surround the fuse wire or strip,hereinafter called lthe fusible conductor. The material which I havefound very satis factory in practice and cheap is flue-dust, such as isdeposited in the ues leading from boiler dre-boxes. A small space is ormay be left uncovered by the finely-divided non-conducting material atsome portion of the tube or vessel to enable the position and conditionof the fuse-conductor to be observed. Con.- tact is made in anyconvenient manner with the ends of the fuse. Thus when a glass tube isused the ends are closed by small caps of brass or are surrounded by.rings or collars of brass or other metal, to which the ends of theflexible conductor are soldered. Connection is then conveniently made`with these caps o1* f rings by spring clips or holders permaiientlyattachedto a case or base in or on which the fuse is supported. E

Figure 1 of the accompanying drawings shows, partly in side elevationand partly in longitudinal section, an electric safety-fuse constructedaccording to thisnvention. Fig. 2 is a side elevation, and Fig. 3 aplan, show ing how the fuse cau be mounted for use.L

Figs. 4 and 5 are similar views to Fig. l, shov ing modifiedconstructions of fuses accordingV to this invention.

In the fuse shown in Fig. 1 the fusible conductor 1, in, the form of alength of copper wire, is embedded in finely-divided insulating andincombustible material f2 of the kind mentioned,inclosed in acylindrical glass tube 3, the ends of which are provided with metal caps4,*to which the ends of the fusible conductor are connected.

5 5 are dished disks or partitions, of suitable materlal-for example,paper--arranged a short distance apart to con-fine the finelydividedmaterial in position and leave a clear space 6 at the central part ofthe tube 3, and shown as completely surrounding the conductor, throughthe middle of which said cou ductor passes, so that the condition -ofthe portion of the conductor 1 traversing this space can be easilyobserved. With the construction Fig. l this observation may be had fromany side of the tube, because the airspace completely surrounds theconductor.

lf`igs'-z?d and 3 showa pair of'spring clips or holders 7 7, betweenwhich the fuse can be easily inserted for use. These clips orholders arefixed upon a base-piece 8 and are provided with binding-screws 9 forplacing the device in an electric circuit. Fig. t shows anotzer way inwhich safety-fuses can be constructed according to this invention. Iuthis oase the fusible conductor l is supported ina longitudinal groove,trench, or recess 10 in a vessel or receptacle ll, made of porcelain orother suitable material, the groove or recess being charged withvfinely-divided or pulverizedmaterial 2, so as to surrround the wire, andthe whole secured together by a cover or lid 12 of suitable material,such as porcelain or glass. A small portion l of the conductor l ispreferably left uncovered and visible, as in the other arrangement, toenable its position and condition to be observed. In the construetionFig. 4 the air-space likewise is shown as completely sonrrounding theconductor, notithstanding the observation can be had from the top of thesheath or vessel only when the cover is removed. This is because Iconsider that for the best results.in the practical use and operation ofthe fuse and the maintenance ofasubstantially uniform fusing point ortemperature the air-space should completely surround the conductor eventhough the inspection, if providedfor, be restricted to one side only.It will also be noted that in both the constructions Figs. l to 4,inclusive, the airspace is central of the length of the tube and isrelatively short as compared with the length of the tube. I have foundthis length and 1ocation of air-space to produce the best results. itbest tends to concentrate the first blowing or rspturing point of thefuse within the airspace.

lhe above-described methods of carrying out my invent-ion are thosewhich I prefer; but I do not limit myself to them. Other methods may beused. Thus instead of surrounding the fusible conductor bythenonconductingincombustible material in a finelydivided form, as abovedescribed, in a glass tube or other receptacle I may make upthe saidmaterial by clompiession or otherwise into a mass-as, for instance, inthe form ofa block or cylinder 13, Fig. -surrounding the fusi bleconductor or having one or more small holes through which the saidconductor may be passed, the said material thus surrounding theconductor and inclosing-an air-space traversed thereby, the holeconstituting the,

airspace, and in which it may be secured and having its end connected tocontact-pieces 4.

The action of 'the improved fuse is as follows: The passage of anexcessive current causes the fusible conductor to be volatilized, themetal being deposited in a finely-divided condition among the particles0f the surroundingr nonconductii1g material. So complete is thedissipation of the metal that it is frequently ditlicult to nd byinspection any trace of it after the conductor has been fused. Thenon-conducting material between the terminals reduces the amount of airin the vessel, prevents the formation of a conductingchain of metallicpartlcles,andforms ahighlyresisting medium. Thus the occurrence of anarc is prevented. For large currents I prefer to use a small fuseconstructed as above described or otherwise according to my inventionand to shunt it by au ordinary fuse or by an electromagnetic or lothereut-out, (indicated diagrammatically at 14 in Fig. 3.) This ordinaryfuse or cut-out is arranged to carry practically' the whole current. Inthe event of an excessive current the ordinary fuse melts or the cut-outacts, but does so with a scarcely-perceptible spark. The fin rupture ofthe circuit then occurs iu the small special fuse.

iVltat I claim is- 1. In a safety-fuse, a fusible conductor combinedwith non conducting material in a finely-divided state traversed by saidcondnctor.

2. In a safety fuse or cut-out, a fusible coud uctor, and a tube orvessel of finely-divided, compressed incombustible nonconductingmaterial surrounding said conductor and inclosing an air-space traversedthereby, substantially as described.

3. A safety-fuse comprising a fusible condnctor., and a tube or vesselcharged with finely-divided non-conductin g material trayersed by saidfusible conductor, substantially' as described.

4.` A safetyfuse comprising a fusible condoctor, a tube or vessel inwhich said fusible conductor is arranged, contact-pieces carried by theends of said tube 'or vessel and connected to the ends of said fuse wireor strip, and finely-divided non-conducting material arranged in saidtube or vessel, substantially as described.

5. A'safety-fuse comprising a fusible conductor, a tube orv vesselinclosing the same, finely-divided non-conducting material surroundingpart only of said wire or strip so as to leave part thereof uncovered,and contacts in connection with the ends of said fusible conductor,substantially as described.

6. A safety-fuse comprising a fusible conductor, a glass tubesurrounding said fusible conductor and provided at its ends with metalcaps to which the ends of said conductor are con nected,inel,-dividednon-condncting inaterial surrounding said conductor, and par titionsarranged to hold said fineiy-divided material in place and to form aclear unobstructed space traversed by said conductor, substantially 'asdescribed for the purpose specified.

7. The combination with an ordinary fuse or cut-out adapted to carryingpractically the whole of the current in the circuit with which it is tobe used, of an additional fuse arranged as a shunt to the ordinary fuse,and compris- XIO ing a fusible'conductor, and a vessel or tube in suchamanner as to leave au air-space about xo charged with finely-dividednon-conducting the fuse-wire. material traversed by said fusibleconductor In testimony whereof I have signed my substantially asdescribed. nume to this specification in the presence of 8. A safetyfusecomprising a fusible contwo subscribing witnesses.

ductor, an inclqeiug sheath or vessel in which WILLIAM MORRIS MORDEY.

said fusible conductor is arranged and sur- \Vitnesses rounded by a massof finely-divided rcfrac- PERCY G. ISIATTOCKS,

tory material placed iu said sheath or vessel,v WM. U. BROWN.

